A factory fresh 640bhp Cadillac CTS-V is already capable of reaching a top speed of 320km/h. But according to Hennessey, there are people who want more.

The Texas-based tuner is ready to offer the 2016 HPE1000 package for the new CTS-V which replaces the compact factory four-lobe Eaton supercharger with two turbochargers. The strengthened 6.2-litre V8 will now have an alarming 1000bhp. With all that mad power, carbon ceramic brakes will be included in the package. A wide bodykit with larger wheels and tyres as well as custom upgrades for the interior round up the rest of the upgrades.

While not officially the world's fastest 4-door sedan yet with a estimated top speed of 386km/h, only 24 owners will be able to enjoy that title when it does become official.

For those who don't have that much need for speed, they can choose the 'milder' 800bhp upgrades that Hennessey Performance Engineering will offer in the future too. The V8 will remain supercharged.